OPTICAL RECORDING MEDIUM AND ITS REPRODUCING DEVICE

摘要

PROBLEM TO BE SOLVED: To normally reproduce a hologram even if dirt or dust is stuck to the hologram at the time of recording such complicated information in the hologram that it may be hardly forged. SOLUTION: Plural syncCHG 3b to determine the timing to read plural information CGH 3a representing card information are formed in the array direction of information CGH 3a so that the pitch and the area of interference fringes of syncCGH 3a may be larger than those of information CGH 3a. The number of light diffracted by syncCGH 3a is different in the array direction, and the number of diffracted light indicates the position of information CGH 3a.